210 PLACENTAL BLOOD FLOW AND TRANSFER OF NUTRIENTS IN SPONTANEOUS FETAL GROWTH RETARDATION IN THE GUINEA PIG

Abstract

Reduced availability of nutrients due to reduced placental blood flow or placental insufficiency is considered the most likely cause of intrauterine growth retardation(IUGR). These two variables, however, have not been measured during spontaneous IUGR. Since the guinea pig has a high incidence of spontaneous IUGR, it was, therefore, selected as a suitable model to explore the mechanisms of IUGR. Simultaneous measurements of maternal placental blood flow, using microspheres, and placental transfer of 14C-α-amino isobutyric acid(AIB) and 3H-3-0-methyl glucose(MG) were made between 32 and 59 days of normal gestation. Small (S) and large(L) littermates were compared to mean litter values. Results are as follows:fetal weight:S-18%,L+12%; placental weight:S-16%,L+14%; blood flow: S-35%,L+27%; total AIB transfer:S-34%,L+29%; total MG transfer:S-18%,L+13%;AIB transfer/g placenta:S-20%, L+16%; AIB transfer/g placenta/ml blood flow(placental efficiency):S+17%,L-13%. Thus in the guinea pig fetal growth is correlated with placental blood flow. IUGR fetuses have a reduced blood flow without a concomitant reduction in the efficiency of the placenta to transfer nutrients. (Supported in part by USPHS, NIH Grant KO4 HD 00116-01 & by the R.S. McLaughlin Found.)